Within the field of watch-making, a conventional architecture is used to make movements, which are provided with striking mechanisms, such as minute repeaters. In such embodiments, the gong or gongs used are each formed by a metal wire, generally circular in shape and placed in a parallel plane to the watch dial. The metal wire of each gong is generally arranged around the movement, in the watch frame and above a plate on which the various parts of the movement are mounted. One end or several ends of each gong is/are fixed, for example by soldering, to a gong-carrier integral with the plate, for example, which may be common to all of the gongs. The other end of each gong may generally be free.
The watch striking mechanism includes at least one hammer actuated at predetermined times. The gong vibration is generated by the impact of the corresponding hammer on the gong in proximity to the gong-carrier. Each hammer generally makes a partial rotation in the plane of the gong(s) so as to strike the corresponding gong and cause it to vibrate in its plane. Part of the vibration of the gong is transmitted to the plate by the gong-carrier.
Depending upon the shape and dimensions of the gong(s) used in a striking mechanism, inadvertent ringing of the gong(s) may occur against neighbouring metal parts in rest mode after the watch has made an abrupt movement. The longer the length of the gong, such as a cathedral gong, including at least two windings around the watch movement, the more likely it is that the problem of inadvertent ringing or accidental resonance will occur. A material with a relatively low modulus of elasticity may also contribute to inadvertent ringing. This is a drawback for a luxury watch provided with a striking mechanism of this type.
One solution to this problem is set out in EP Patent Application No. 1 914 606 A1. In this Patent Application, one or more mechanical noise insulators are provided for one or more gongs of a striking mechanism. This striking mechanism includes two cathedral gongs, secured via one end thereof to a single gong-carrier. The mechanical insulators are, for example, at least one separator piece placed between the windings of the gongs, in addition to rings regularly distributed over each gong. However, this insulator arrangement has the drawback of having a multitude of static mechanical insulator elements in the watch case, in direct proximity to each gong, which may create disturbances in the strike mode of each gong. Moreover, this set of noise insulators for each gong greatly impairs the aesthetic appearance of this type of striking mechanism.
DE Patent No. 443 387, which discloses a locking device for an alarm watch striking mechanism, may also be cited. To achieve this, a magnetic element holds the strike hammer in a wound position at a distance from the gong, when the coil of the magnetic element is powered with electricity. When the electric power to the coil is interrupted, the hammer is released and can strike the gong. However, this does not prevent the gong from striking neighbouring metal parts when the striking mechanism is in rest mode, which is a drawback.
The use of a magnetic element in the striking mechanism is also known from U.S. Pat. No. 2,054,765, but the magnetic element is only used in cooperation with a metal disc of the mechanism for adjusting the speed of the striking mechanism and not for providing gong insulating means.